Electrical energy storage capacity detector, such as a battery gauge, can be used for detecting the capacity of energy storage units, such as Lithium Ion (Li-Ion) batteries which have different types of chemistries like Li-Ion manganese, Li-Ion cobalt, Li-Ion phosphorus, etc. These different types of chemistries may result in different voltage and current characteristics, such as different charge limit voltage characteristics and different voltage versus capacity characteristics. For instance, the charge limit voltage of Li-Ion battery of manganese chemistry can be 4.2V, the charge limit voltage of Li-Ion battery of cobalt chemistry can be 4.2V, the charge limit voltage of Li-Ion battery of nickel-cobalt manganese (NCM) chemistry can be 4.1V, and the charge limit voltage of Li-Ion battery of phosphate chemistry can be 3.6V.
Some typical traditional methods to measure the battery pack capacity include Coulomb counting and cell voltage measurement. The Coulomb counting method measures the net current flowing in the battery by counting the passing charge in order to measure the battery capacity. However, some drawbacks may exist since voltage to frequency converters, higher frequency situation, and frequency compensation for temperature variations may need to be taken into consideration.
The cell voltage measurement method compares an actual battery cell voltage with absolute capacity thresholds of a charged battery. To accommodate different types of battery chemistries, capacity thresholds may need to be set through trimming or a non-volatile integrated memory of a controller.
Both of these methods may require a relatively expensive micro-controller or an extensive circuitry compatible with different battery chemistries and different current ranges in different applications.